A prosecutor says the only fingerprints found on the rifle used in the Washington sniper attacks belonged to teenage suspect John Lee Malvo.
The authorities are also linking another Maryland shooting to 17-year-old Malvo and John Allen Muhammad, 41.
Nearly a month before last month's shootings began in the Washington area, a man was shot six times at close range as he locked up his restaurant in suburban Clinton, Maryland. Paul LaRuffa, 55, survived.
LaRuffa's attacker took his laptop computer. Authorities have confirmed the computer was found in the suspects' car when they were arrested.
Malvo and Muhammad, 41, are now accused of shooting 19 people, killing 13 of them, in Alabama, Georgia, Louisiana, Maryland, Virginia and Washington. Two other shootings, in Washington state, are under investigation.
At the teenager's initial court appearance in Virginia, Fairfax County prosecutor Robert Horan Jr said eyewitnesses had spotted Malvo at three of the fatal crime scenes.
A few miles away, Muhammad made his first appearance in a Virginia court and a judge said he would appoint a lawyer for him.
Last week, Horan said without elaborating that there was "an equal possibility" either Malvo or Muhammad gunned down FBI analyst Linda Franklin outside a Home Depot on October 14 in Fairfax. Malvo is charged in that case.
Horan would not discuss evidence in detail, but he said after the hearing that only Malvo's fingerprints were found on the .223-calibre Bushmaster XM15 semi-automatic rifle authorities believe was used in the killing spree. The gun was found in the men's car after their arrest on October 24th.
Malvo's court-appointed lawyer, Michael Arif, dismissed the importance of the fingerprints. He said Malvo, who faces two counts of capital murder and a firearms charge, would plead not guilty. Malvo will be held in an adult jail until a December 5th hearing.